LeBron James waited until the fourth quarter to electrify AmericanAirlines Arena on Friday night, and when it finally happened a collective sense of relief poured out of the sold-out crowd.

Finally, these two-time defending champions seemed to care.

But that familiar feeling of purpose was fleeting. Moments of greatness by James late in games have sparked brushfires for the Heat’s offense going on four seasons now, but the passion and energy arrived too late. The Ides of March are here and with it another Heat loss, this time a 111-107 defeat to the woeful Denver Nuggets.

This shrine of basketball on Biscayne Bay hasn’t known tedium for some time, but a little bit of that stuff has crept into the cracks of the hardwood in recent days. The Heat (44-19) has lost five of its past six games and is 3-5 in March.

“A tough loss at home, and we just have to figure it out,” Heat coach Erik Spoelstra said. “It’s not the way this streak started. Sometimes, it just happens to you in this league where things turn and moment changes and you find yourself in a hole you feel like you can’t get out of. Obviously, we’ll be able to get out of it. When? We don’t know.”

Said James: “We’ve been here before. It has been a while, but we’ve been here before, and this moment will either define our season or end our season. We always have one defining moment, and this is it right here for us.”

Before the game, Spoelstra emphasized to his players the need to substitute more freely in order to conserve energy, and the plan worked well early on. The Heat took a 30-20 lead after the first quarter, but, once again, the team was undone by turnovers.

Miami committed 20 in all, which the Nuggets converted into 22 points. Meanwhile, the Heat shot just 29.2 percent from three-point range (7 of 24) despite Ray Allen going 5 of 7 from beyond the arc.

“More than anything, more than our shot selection, for two games in a row, was the turnovers,” Spoelstra said. “Every time we had an opportunity to get back in the game, take control of the game or shift the momentum, it was an uncharacteristic turnover that swayed the tide, and we have to clean it up in that department.

“Those empty possessions — you don’t know where those lead if you don’t make those mistakes.”

James and Chris Bosh were both 0 for 4 from three-point range, and Heat forward Shane Battier — the starting lineup’s constant mismatch from the outside — only attempted one shot from long distance.

Poor shooting from the outside suggests fatigue, but James said that isn’t a factor. After all, the Heat was reeling off 27 wins in a row at this time last year.

“We’re just not playing well,” James said. “We’re just not playing well, and it’s a league where it can turn to quicksand quick we have to figure it out, and we have to get better, and it doesn’t get any easier for us with Houston coming into our building on Sunday.”

A pair of free throws by Nuggets firebrand Kenneth Faried — he banked in the first — gave the visiting team a five-point lead with 65 seconds to play, and the Heat was done. James attempted a pair of three-pointers in the final minute and missed them both. The second, last-gasp miss came with 12 seconds to play, and Faried pulled down the rebound. He made two more free throws on the other end to hand the Heat its third loss this season to the dregs of the Western Conference — Denver, Utah and Sacramento.

“Something is off,” said Dwyane Wade, who had 19 points.

Faried led the Nuggets with 24 points, going 9 of 15 from the field to go along with 10 rebounds. Point guard Ty Lawson had 13 points, going 9 of 10 from the free-throw line. Three reserves scored in double figures for the Nuggets — Darrell Arthur (18), Evan Fournier (14) and J.J. Hickson (11).

Allen led the Heat with 22 points in 29 minutes of work off the bench. James had 21 points, going 8 of 17 from the field and 5 of 7 from the free-throw line. He also had six rebounds and six assists. James had just five points in the fourth quarter, going 1 of 4 from the field. In the Heat’s loss to Brooklyn on Wednesday, James failed to score in the fourth quarter.

The Heat led by 14 points in the first half but trailed for the entire second half. Wade was 8 of 18 from the field. Mario Chalmers was 7-of-11 shooting for 16 points. He added six assists and four rebounds.